[Problem] A preparation of forming bubbles of carbon dioxide gas which is put into a micro-bubble generator is realized, unlike a conventional tablet, as a tablet which can retain an ability to neutralize and remove completely chlorine contained in tap water from start of dissolution of the tablet inside the micro-bubble generator to the completion of dissolution thereof, thereby providing a method for producing micro-bubbles of carbon dioxide gas by using the tablet and a device thereof. [Solution] There is provided a method for producing carbon dioxide gas/micro-bubbles mixed water in which a carbonated bathing agent is a tablet which is 7 mm or more both in tablet diameter and tablet thickness, 15 kg or more in tablet hardness, 10 wt% or less in tablet friability and from 5.5 to 9.0 in pH immediately after dissolution of the tablet in hot water and the carbonated bathing agent contains at least one of the following body rendering agents and contains at least one of the following chlorine neutralizing compounds.
